Mirrored discovering disasters in the f file
It was my teammate Ruth who has pointed at a striking symmetry when we analyzed my recent game in our traditional pizza round after the team match. First, and most important, our team has won 5-1 against a stronger rated opponent. Woo-hoo!
My +70 rated opponent had served a King's gambit which I declined. Besides the first declining move I didn't know the theory, so I used 30 minutes against his one minute in the opening. In my last move, I had just pinned his King's Knight and he had taken my center pawn. And here I took back with my pawn which was a gross mistake.
Black to move
The white King's Knight must not be allowed to enter the fifth rank, attacking the vulnerable point f7. Thus, it was mandatory to keep control over the square e5, playing Nc6. After 5.-dxe5? 6.Bxf7+! I already had to fight against loss. Of course, the Bishop was taboo, and I had to play Kf8. My opponent brought the Queen's Knight and Bishop into play, depinned his King's Knight, all reasonable plans, but I think he somehow missed to bring all his forces, including his Queen, castle queenside and open the center and attack my exposed King in the center. On the 18th move, we came to the following very sharp position.
White to move
With 17.-Nd4 I had attacked his Rook on f5, and here it was, the symmetric mistake, retiring the Rook to f2 instead of f1. The discovered attack looms, but the Knight has no useful goals. Not yet. Thus I played 18.-b5! and now the Bishop isn't allowed to move. Yet my opponent made the disaster complete, retiring 19.Bb3, and now the discovering move Nxb3 wins material. Game over!
Interestingly, he could have kept the game even by no less than three alternatives! Firstly the counter-attack c3, secondly the trade Nxf6+ and thirdly the trade Bxf6. Even the pawn "sacrifice" b4 was possible, followed by Bxb4+ and c3.